Testing system for telephone-lines.



No. 717,973. PATENTBD JAN. 6, 1903.

w. w. DEAN. V TESTING SYSTEM FOR TELEPHONE LINES.

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PATENTED JAN. 6, 1903.

- W. W. DEAN. TESTING SYSTEM FOR TELEPHONE LINES.

APPLIQATION FILED AER. 5 1901. T 1 R0 MODEL 7 I 2 SHEETS-SHEET 2.

v a siren TATES SWITCHBOARD AND SUPPLY COMPANY, OF A CORPORATION OFILLINOIS.

CHICAGO, ILLINOIS,

TESTING SYSTEM FOR TELEPHONE-LINES.

SPECIFICATION forming part of Letters Patent NO. 717,973, dated January' 6, 1903.

Application filed April 5, 1901- Serial No. 54,423. (No model.)

phone-Lines, of which the followingis a full,

clear, concise,and exact description,reference being had to theaccompanying drawings, forming a part of this specification.

My invention relates to a testing system for telephone-lines. Testingsystems as heretofore commonly employed have embodied means whereby theoperator may touch the tip of her calling-plug to the testing-terminalof the switchsocket to thereby send, if the line is busy, a currentthrough the responsive device of the testing systemas, forinstance,through the receiver of the operators telephone set. The operatorhearing a click in her telephone will know that the line is busy. On theother hand, if she bears no click she will know that the line is idle;In these systems as usually constructed heretofore a specialtest'terminal has been provided upon the switchboard, to which the tipof the test ing-plug is adapted to be touched in the making of the test.The potential of the special testing-terminal may be readily adjusted tothe required amount to givethe desired. low click in the operatorstelephone. Moreover, due to the employment of the specialtestingterminal, the touching of the tip of the plug thereto to olferanother path for the current does not produce a click in the telephoneof the subscriber whose line is being tested.

The object of the present invention is to provide a testing systemparticularly adapted to that class of telephone-lines wherein no specialtestingterminal is provided upon the switchboard, one of the mainline-terminals of the switch-socket or a terminal connected with oneside of the talking-circuit during a connection being relied upon fortesting purposes. In this type of switchboard the potential at theswitchboard-terminal used for testing will depend upon the voltage, ofthe source of electricity employed for energizing the microphone at thesubstations and the various signaling apparatus. The voltage of thisbattery will be determined by the length of the lines and the nature ofthe signaling apparatus employed and cannot, therefore, be readilyadjusted to suit the requirements of the testing apparatus. Thepotential at the testing-terminal is therefore considerably greater thanit is Where a special test terminal is employed. When, therefore, thetip of the testing-plug is touched to the line-terminal, thus affordingan additional path for the current and lowering the potential of theline-terminal, a click will be caused in the receiver of the subscriberwhose line is being tested, and due to the high potential of the lineterminal this click will be of such a magnitude as to be quiteobjectionable. It is necessary, therefore, in providing a test for thistype of telephone-line to obviate this objectionable click in thesubscribers telephone. Accordingly I provide for each operator atesting-circuit having a high resistance and preferably also a highimpedance and which preferably takes the form of a relay or testresistance device, which is adapted to be connected with all of thecords controlled by said operator, the relay being normally in circuitwith the tips of all of the calling or testing plugs. any one of theplugs is touched to the testingterminal upon the switchboard, a currentwill traverse the relay or test device if the line is busy. The relay ordevice thereupon acts to control a local circuit containing a suitablesource of electricity and the operators telephone or other responsivedevice. The strength of the current flowing in the local circuit may bereadily adjusted as desired, and in this manner the strength of theclick in the operators telephone may be suitably adjusted. By making therelay of high resistance and with many turns the current flowing When,therefore, the tip of through the relay and test-conductor will be sincethe added path through the testing apparatus is of high resistance, and,moreover, due to the impedance of the relay the variation of thepotential is gradual. The result is that the testing-current traversesthe relay and test-circuit without in any manner affecting the receiverof the subscriber whose line is being tested. While I preferably provideone relay or responsive device for all of the calling-plugs controlledby one operator, this, of course, is not an essential feature of theinvention, as a relay may be provided for each connecting-cord or forsuch number of connecting-cords as may be desired. I further providemeans whereby the insertion of a calling-plug in the switch-socket of acalled subscriber will serve to automatically disconnect the testingdevice or relay from the tip of the plug and whereby the removal of theplug from the socket serves to automatically reconnect the testingdevice or relay with the tip of the calling-plug.

A further feature of my invention is the provision of means whereby thetesting apparatus may be automatically connected with and disconnectedfrom the tip of the callingplug without the provision of a thirdterminal upon the connecting-plug, as has been the usual practiceheretofore.

I have illustrated my invention in the accompanying drawings, in which-Figure 1 is a diagram illustrating two telephone-lines and thecentral-station apparatus of my invention. Fig. 2 is a diagram showing amodification of the central-station apparatus. Fig. 3 is a diagramshowing the manner in which a single testing-relay is asso ciated with aplurality of cord-circuits.

Like characters refer to like parts in the several figures. 4

The telephone-lines may be of any approved type, and I have illustratedtelephone-lines of the well-known Dunbar type. It will be understood,however, that my invention is equally applicable to anyspecific form oftelephone-circuit. I have shown the substation A provided with two limbsa ct, extending to the central station and terminating, respectively, insprings 0. a spring a? normally resting against contact 1 and the spring00 against contact 2. Between the contacts 1 and 2 the battery andindividual indicator 0 are connected. Contact 4 is connected withline-springs cl d upon the several sections of the switchboard, and thecontact 5 is connected with the line-thimbles d d The relay b isconnected between the contact 5 and ground. IVhen the relay 1) isenergized, springs a a are attracted to cut out indicator c and toconnect limbs a and ct with the terminals of the switch-socket. At thesubstation the usual microphonefand receiver f are connected with thecontact 8, and the switch-hook f which is adapted to engage contact 8when the receiver is lifted, normally rests against contact 7, which isconnected to ground through belly" and condenser 13.

The specific form of telephone-line herein illustrated is not claimed inthis application.

The substation B (shown upon the right) is similar to that described inconnection with subscriberA,and like parts have been indicated by thesame reference characters.

The answering-plug p is provided with the usual tip 19 and sleeve 19 theformer connected with strand tand the latter with strand 8. Thecalling-plug o is provided with tip 0 and sleeve 0 the former beingconnected with strand t and the latter with strand 3. The strands t and25 are united through a condenser Z and the strands s and 3 through acondenser Z. Thecentralenergizing-battery r is connected at one polewith the strands if and 25 through relays h and k, having a resistanceusually of about fifty ohms. The opposite pole of said battery 0* isconnected with strands s and .9 through relays h and it, which also havepreferably a resistance of about fifty ohms. One pole of the battery isgrounded, as shown. The relay h controls contacts m and 14, and therelay h controls contacts on and 13, the contact m being connected withone side of battery 1" and the con tact m with the opposite side. Incircuit with the contacts is the lamp m, whichconstitutestheclearing-outsignal. Likewisethe relay 76 controls contacts12 and 16, and the relay it" controls contacts 0) and 15. In circuitwith the contacts is the clearing-out lamp 0. Connected with thecontact-spring v and insulated therefrom is a supplemental contact '0adapted when relay is is energized to engage contact 11. The spring U3and contact 11 are interposed in the circuit of strand t, and whenspring '0 rests against contact 10 said strand is opened, and is closedwhen spring 11 is moved against contact 11. Contact 10 is connected toground through relay a: or other test receiving and responsive device,which preferably possesses high resistance and impedaucesay five hundredohms. The relay 0c is common to a plurality of cord-circuits, usuallycommon to all of the cords controlled by one operator, and theconductors extending to the contacts 10 of the different cord-circuitsbranch from the point 9:. The relay :0 controls contacts m 9, the formerbeing connected with ground and the latter being in the present instanceconnected through the tertiary winding 1" of the operators telephoneset. The secondary winding 6* is connected between the contacts 17 and18 of the listening-key and is included in circuit with a condenser ZThe springs i i of the listening-key are connected, respectively, withthe strands t and s. The primary i and the microphone i are connectedbetween the opposite sides of the battery 7'. The telephone-receiver 11is connected in circuit with the secondary 1?. The ringing-key g isconnected in the strand if and normally rests against contact 19 and isadapted to engage contact 20 to close circuit through generator g.

If subscriber A desires to converse with subscriber B, he lifts histelephone-receiver from the hook, thereby closing the circuit of batteryr through indicator 0 to actuate the same. The operator thereupon liftsanswering-plug p and inserts the same in the circuit belonging to lineA. Circuit is thus closed from ground through battery r, strand 8,sleeve 19 thim bled relay 6, to ground, and said relay is energized toattract springs a and a thereby cutting out of circuit indicator c andconnecting the limbs a a with the line-terminals d (1 The operator thenbridges in her telephone in the usual manner and receives the number ofthe called subscriber. Learning that subscriber B is wanted, she liftsthe calling-plug 0, which also serves as a testing-plug, and touches thetip 0 thereof to the thimble oZ belonging to subscriber B. If subscriberBis connected for conversation at another section of the switchboard,the thimble d will be raised to a potential different from the earth,due to its connection with the energizing-battery r at the other sectionof the switchboard. When, therefore, the tip 0 is touched to the thimble(1 current will flow from the thimble through the tip to strand t,thence through contacts 41 and 10 and relay 0a to ground. The circuit ofbattery r may be traced over the strands of the cord-connector, at thesection of the switchboard where connection is made, thence to thesleeve of the plug and the line'thimble to thimble d at the board wherethe test is being made, thence to earth by the path above traced. As therelay 0 is of very high resistance, the current thus shunted through therelay is quite small in quantity and does not materially lower thepotential of the thimble 01*. Moreover, since the relay possesses highimpedance the current is drawn off through the relay gradually, andwhatever lowering of potential takes place at the test-thimble takesplace gradually. Consequently the called subscriber, who is inconversation through a connection at another section of the switchboard,hears no objectionable click in his telephone, due to the test. Theenergizing of relay 0c closes circuit of battery 1' through tertiarywinding t", contacts 9 and 00 to ground and back to the battery. Thecurrent through the tertiary winding induces current in the secondary*3, which traverses the operators telephone-receiver. The operator thushears a click in her telephone when the relay is actuated, and the relayis actuated whenever the tip of the testing-plug is touched to thethimble of a line which is connected for conversation.

Assuming that the operator finds the line plug 0 in the switch-socketbelonging to subscriber B. The insertion of the calling-plug through therelays 7i and 7c.

0 in the socket belonging to subscriber B closes the circuit of battery'1' from ground through relay 7i), strand 3, sleeve 0 thimble 61 throughrelay Z) to ground. Relay 7) is thus actuated to connect limbs a a ofthe line B with the terminals of the switch-socket, and relay 7c isenergized to separate contacts '0 and 10, thereby disconnecting relay 0:from the testing-tip 0 and closing together contacts '0 and 11, therebycompleting the continuity of the strand t. The operator then depressesthe ringing-key g, and calling-currents from generator g pass throughtip 0, line-spring d, limb ct, to ground through the bell f therebyactuating the bell. Subscriber B thereupon responds and lifts hisreceiver from the hook, thus closing together the limbs a and a. Theenergizing of relay is also closes together contacts '0 and 15, therebycompleting the circuit of battery 1" through the lamp 1) to light thesame. When subscriber B lifts his telephone from its hook, ,th usclosing together limbs a and a, the relay kis energized to open thecircuit through the lamp, and the operator seeing the lamp extinguishedknows that subscriber B has responded. The circuit of battery r duringconversation is closed through relays k and 7c, strands t and s, andlimbs a, and a of the line B. The circuit of battery r is also closedthrough relays 7t and h, strands t and s, and limbs a and a of line A.The circuit through lamp m is thus opened. Accordingly the lamps m and'v are extinguished while the subscribers are in conversation.

, \Vhen the subscribers have completed conversation, they hang up theirreceivers, thus separating the limbs a. and a, at the substations andopening the circuit of battery r The relays Jr and remain energized,since a path for the current is afforded to ground through the relays bb. The deenergizing of the relays h and 79 while the relays 7t and it"remain energized closes the local circuits through the lamps m and 1;,thereby lighting the same ITO and giving the signal for disconnection.

Should either subscriber-as, for instance, subscriber A -desire areconnection with anothersubscriber, he can by oscillating hisswitch-hook in the usual manner alternately energize and deenergizerelay h to light and extinguish lamp m, and thus signal for a newconnection. \Vhen the operator receives the signal for disconnection,she withdraws the plugsp and 0 from the sockets, and the circuits ofbattery r through the relays 7t and k are thus opened to deenergize saidrelays and open the circuits through the lamps m and v. The deenergizingof the relay k separates spring 12 from contact 11 and closes the sameagainst contact 10, to thereby open the strand (6 and connect the tip 0to ground through the relay a In Fig. 2 I have illustrated amodification of my invention in which the contacts 00 and 9 of relay atare connected directly in circuit with the telephone-receiver '5 insteadof.in circuit with a tertiary winding i. The relay-contacts 00 and 9thus directly control the circuit containing the telephone-receiver. Itwill be understood that instead of a telephone-receiver any otherresponsive device may be employed for testing purposes. It is alsoevident that the relay 00 may be replaced by any other test-responsivedevice or testindicator, but without the advantage of some of thefeatures herein described.

I disclaim herein the matter claimed in the application of Francis IV.Dunbar for telephone-switchboard filed August 17, 1900, Serial No.27,131.

Having described my invention, what I claim as new, and desire to secureby Letters Patent, is

1. In a telephone system, the combination with a telephone-line having aplurality of testing-terminals,of testing apparatus includ ing aplurality of testing-contacts, a relay common to said contacts and incircuit therewith, a responsive device controlled by said relay andactuated whenever a testingcurrent flows over the testing-circuit fromany of said contacts, substantially as described.

2. The combination with telephone-lines having each a testing-contactconnected directly with one side of the talking-circuit, of testingapparatus including a plurality of testing-terminals, a relay common tosaid terminals in circuit therewith, and a responsive device controlledby said relay, substantially as described.

3. The combination with a telephone-line and a charging source ofelectricity, of a testing-terminal for said line connected directly withone side of the talking-circuit, and testing apparatus including atesting-contact, a relay in circuit therewith, a responsive devicecontrolled by said relay, and means for automatically disconnecting saidrelay from the circuit when a connection is made with the line,substantially as described.

4. The combination with a telephone-line having one of the main-lineterminals serving as a test-terminal, of testing apparatus comprising atesting-terminal, a relay in circuit therewith and a responsive devicecontrolled by said relay, substantially as described.

5. In a telephone system, the combination with a telephone-line havingtesting-contacts, of testing apparatus including a testing-terminaladapted to be brought into contact with the testing-contacts of saidline, a relay normally connected with said testing-terminal, aresponsive device controlled by said relay, and means for disconnectingsaid relay from said testing-teri'ninal, substantially described.

6. In a telephone testing system, the combination with aconnecting-plug, of a relay normally connected with the terminalthereof, a responsive device controlled by said relay, and means fordisconnecting said relay from said terminal when the plug is inserted ina switclrsocket, substantially as described.

7. The combination with a plurality of connecting-plugs, of a relaynormally connected with the terminals of said plurality of plugs, aresponsive device controlled by said relay, and means controlled by eachplug for disconnecting said relay from the terminal thereof,substantially as described.

8. The combination with a connecting-plug and the strand associatedtherewith, of a relay, means for normally connecting said relay with theterminal of said plug, and for opening the circuit through said strand,a responsive device controlled by said relay, and means actuated by theinsertion of the plug in a switch'socket for disconnecting said relayand for completing the circuit through said strand, substantially asdescribed.

9. The combination with a connecting-plug and a pairof strandsassociated therewith, of a relay normally connected with one of saidstrands, a responsive device controlled by said relay, and anelectromagnetic device controlled by the circuit through the other ofsaid strands, for disconnecting said relay from the terminal of the plugnormally connected therewith, substantially as described.

10. The combination with a connectingplug, and the strands associatedtherewith, of a relay and a responsive device controlled thereby, meansfor normally connecting said relay with one terminal of said plug andfor opening the strand associated with said terminal, and anelectromagnetic device controlled by the circuit through the otherstrand for disconnecting said relay and completing the circuit throughsaid first mentioned strand, substantially as described.

11. The combination with a connectingplug, having a pair of strandsconnected with the respective terminals thereof, of a relay normallyconnected with one of said strands, a responsive device controlled bysaid relay, an electromagnetic device for disconnecting said relay fromsaid terminal, and means for closing circuit through saidelectromagnetic device and said second strand upon the insertion of saidplug in a switch-socket, substantially as described.

12. The combination with a connectingplug, of a testing device normallyconnected with one terminal thereof, means for closing circuit throughthe other terminal of said plug upon the insertion of the same in aswitclrsocket, and means operated by current over the circuit so closedby the plug to disconnect said testing apparatus from the firstmentionedterminal, said other terminal being included in the talking-circuit whena connection exists, substantially as described.

13. The combination with a connectingplug, of testing apparatus normallyconnected with the tip of said plug; means for closing circuit throughthe sleeve of said plug upon the insertion of said plug in aswitch-socket,

IIO

and means operated by current over the circuit so closed to disconnectsaid testing apparatus from said tip, said sleeve forming part of thetalking-circuit when a connection exists, substantially as described.

14:. The combination with a connectingplug having a pair of terminalsand strands connected with said respective terminals, of

testing apparatus, means for normally connecting said testing apparatuswith one terminal of said plug and for opening the strand connected withsaid terminal and anelectromagnetic device associated with the otherstrand and adapted to be energized when the plug is inserted in theswitch-socket to dis connect said testing apparatus from the terminalnormally connected therewith, substantially as described.

15. The combination with a connectingplug and a pair of strandsconnected with the terminals thereof, of a source of energy and anelectromagnet bridged between said strands one side of said source beingconnected with a third conductor, testing apparatus, means for normallyconnecting said testing apparatus with one terminal of said plug and fornormally opening the strand connected with said terminal, atelephone-line having one limb of the talking-circuit connected withsaid third conductor, and means for closing the circuit of said sourcethrough said electromagnetic device, the limb of said telephone-line andsaid third conductor upon the insertion of the plug in" theswitch-socket to thereby actuate said electromagnetic device anddisconnect said testing apparatus from the terminal normally connectedtherewith, substantially as described.

16. The combination with telephone-lines having testing-contactsconnected directly with one side of the talking-circuit when the linesare switched for use, of a cord-circuit and a central source of currentto furnish current for talking associated with the lines testingapparatus comprising a testing-terminal to cooperate with one of saidcontacts in testing, a test-responsive device in circuit with saidterminal, the testing-circuit being of high resistance whereby when abusy line is tested the change of current therein is reduced, andautomatic means to remove said high resistance from the circuit when aconnection is established, substantially as described.

17. The combination with telephone-lines having testing-contactsconnected directly with one side of the talkingcircuit when the linesare switched for use, of a cord-circuit and a central source of currentto furnish current for talking purposes associated with the lines,testing apparatus comprising a testingtermimal to cooperate with one ofsaid contacts in testing, a high resistance and testresponsive device incircuit with said terminal, and electromagnetic means to remove theresistance during the conversation, substantially as described.

18. The combination with telephone-lines having testing-contactsconnected directly with one side of the talking-circuit during aconnection, of a cord-circuit and a central source of current to furnishcurrent for talking purposes associated with the lines, testingapparatus comprising a testing-terminal to cooperate with one of saidcontacts in testing, a high-resistance and test-responsive device incircuit with said terminal, and means to automatically remove the sameduring a conversation, substantially as described.

19. The combination with telephone-lines having testing-contactsconnected directly with one side of the talking-circuit duringconversation, of a cord-circuit and a central source of current tofurnish current for talking purposes associated with the lines, testingapparatus comprising a testing terminal to cooperate with a test-contactwhen testing, a high-resistance and test-responsive device in circuitwith said terminal, and means to antomatically remove the same upon theconnection of the cord-circuit with the line, substantia'lly asdescribed.

20. The combination with telephone-lines having testing-contactsconnected directly with one side of the talking-circuit duringconversation, of a cord-circuit and a central source of current tofurnish current for talkingpurposes associated with the lines, testingapparatus comprising a testing-terminal to cooperate with said contacts,a test-responsive device in circuit with said terminals, thetesting-circuit being of high resistance to prevent a large variation ofthe current upon the line when tested, and means automatically actuatedwhen a connection is established for cutting out said resistance,substantially as described. Y

21. The combination with telephone-lines having testing-contactsconnected directly with one side of the talking-circuit during aconnection,ofacord'circuitandcentralsource of current to furnish currentfor talking purposes associated with the lines, testing apparatuscomprising a testing-terminal to 006perate with said contacts, atest-responsive device in circuit with said terminal, said lattercircuit being of high resistance or impedance to prevent a large orsudden variation of current on the line when tested, and electromagneticmeans automatically energized when a connection is established to cutout said high resistance or impedance, substantially as described.

22. The combination with telephone-lines having testing-contactsconnected directly with one side of the talking-circuit duringconversation, of a cord-circuit and central source of current to furnishcurrent for talking purposes associated with the lines, testingapparatus comprising a testing-terminal to cooperate with said contacts,a test-responsive device in circuit with said terminal, the test-circuitbeing of high resistance and impedance to'prevent a large and suddenvariation of current on the line when tested, and ing-circuit beingcommon to the said cordmeans to automatically cut out said resistanceduring a conversation, substantially as described.

23. The combination with telephone-lines having testing-contactsconnected directly with one side of the talking-circuit during aconnection, of a cord-circuit and a central source of current to furnishcurrent for talking purposes associated with the lines, testingapparatus comprising a testing-terminal to cooperate with saidtesting-contacts of the lines, a testing-conductor connected with saidtestterminal, a high resistance in said conductor to prevent an excessflow of current therethrough when testing, and a relay operated over astrand of the cord-circuit actuated during a conversation to remove saidresistance, substantially as described.

24. The combination with telephone-lines having test-contacts connecteddirectly with one side of the talking-circuit during a connection, ot acord-circuit and a central source of current associated with the lines,a testing apparatus comprising a tip-contact upon the plug of thecord-circuit, a testing-conductor from said contact, a high resistancein said conductor, and a relay operated by current flowing over atalking-strand of the cord-circuit during a conversation to remove saidresistance, substantially as described.

25. The combination with atelephone-line of a testing-contact therefor,a cord-circuit, a testing-circuit completed over the tip-strand of thecord-circuit, a high resistance in said circuit, and a relay operated bycurrent flowing over one of the talking-strands of the cord-circuit toremove said resistance, substantially as described.

26. A telephone-line having a testing-com tact, a cord-circuit, atesting-circuit completed over the tip-strand of the cord-circuit, atest-responsive device in said circuit, said circuit being of highresistance to cut down the flow of current therein to the desiredextent, and a relay operated over a talkingstrand of said cord-circuitto reduce the resistance of said circuit, substantially as described.

27. A telephone-line having a testing-contact, a cord-circuit, atesting-circuit completed over the tip-strand of the cord-circuit, atest-responsive device in said circuit, said circuit being of highresistance to cut down the flow of current therein to the desiredextent, and a relay operated over the talkingstrand of the cord-circuitto remove said device, substantially as described.

28. The combination with telephone-lines having testing-contactsdirectly connected with one side of the talking-circuit when the linesare switched for use, a plurality of cordcircuits and a central sourceof current to furnish current for talking purposes associated with thelines, testing apparatus comprising a testing-terminal for eachcord-circuit to cooperate with said contacts in testing, thetestcircuits and being of high resistance, and a test-responsive devicein said circuit, and means automatically actuated to disconnect saidtesting-circuit from any of the cord-circuits when a connection isestablished thereby, substantially as described.

29. The combination with telephone-lines having testing-contactstherefor connected directly with one side of the talking-circuits duringconversation, of a plurality of cordcircuits and a central source ofcurrent associated therewith and adapted to furnish current for talkingpurposes, testing apparatus comprising a testing-circuit common to saidcords, said circuit being of high resistance and impedance, attest-responsive device in said circuit, and means to automaticallydisconnect said circuit when the cord-circuits are in use forconversation, substantially as described.

30. The combination with telephone-lines, of a testing-contact therefor,cord-circuits, a testing-circuit common to said cord-circuits andcompleted over the tip-strand of each, the said circuit being of highresistance, and a relay for each cord-circuit and operated by currentflowing over one of the talkingstrands of the cord-circuit to removesaid resistance from the corresponding cord-circuit, substantially asdescribed.

31. The combination with telephone-lines having testing-contacts, ofcord-circuits, a testing-circuit common to said cord-circuits andcompleted over the tip-strand of each, a test-responsive device in thecommon portion of said circuit, means to cut down the fiow of currenttherethrough, and a relay for each cord-circuit operated over the sleevetalkingstrand thereof to disconnect the said common portion of thecircuit, substantially as described. v

32. In a telephone system, the combination with two or moretelephone-line circuits, each provided with one or more spring jackswitches or line-terminals, one or each of said switches being providedwith a testing-contact, said testing-contact being connected to one sideof the talking-circuit of said line when switched for conversation, of acord-circuit terminating in a plug at each end, said plug being providedwith contact-terminals adapted to register with the contacts of saidspring-jack switches, an operatorslisteningkey associated with saidcord-circuit and adapted to cut the operators telephone in circuit, asource of current associated with said cord-circuit and adapted tofurnish current over said line when switched for conversation, twosupervisory signals associated with said cord-circuit and adapted to beoperated when connection is made with the line, and means for renderingsaid signals inoperative by a switch at the distant end of each of thelines, said switches controlling the current flowing over each of saidlines, a test-responsive device associated with said cord-circuit andcommon to two or more of said cord-circuits and operated over a circuitof relatively high resistance, said circuit being completed between thetesting-contact of the testplug and the testing-contact of thelineterminal when the line tested is switched for conversation, anelectromagnetic device associated with the said cord-circuit andcontrolling a contact in the circuit of one of said supervisory signals,said electromagnetic device being adapted to operate during conversationand to disconnect said test-receiving circuit and to substitute therefora circuit adapted for conversation, whereby the operator may cut in hertelephone-circuit by means of said cut-in key after connection has beenestablished without restablishing the test-receiving circuit and wherebythe line-circuit is subject to no undue disturbance when the testismade.

33. A telephone-line circuit provided with one or more spring-jackswitches or lineterminals, one oreach of said switches being prot videdwith a testing-contact, said testing-contact being connected to one sideof the talking-circuit of said line when switched for conversation, acord-circuit terminating at one end in a plug provided withcontact-terminals adapted to register with the contacts of saidspring-jack switches, an operators listening-in key associated with saidcord-circuit and adapted tocut the operators telephone into circuit, asource of current associated with said cord-circuit and adapted tofurnish current over said linewhen switched for conversation, asupervisory signal associated with said cord-circuit and adapted to beoperated when connection is made with a line and means for renderingsaid signal inoperative controlled by a switch at the distant end of theline-circuit, said switch altering the flow of current over said line, atestresponsive device associated with said cordcircuit and operated overa circuit of relatively high resistance, said circuit being completedbetween the testing-contact of the test-plug and the testing-contact ofsaid lineterminal when the line tested is switched for conversation, anelectromagnetic device associated with the said cord-circuit andcontrolling the circuit of the said supervisory signal at one point andadapted to operate during conversation and to disconnect saidtest-receiving circuit and substitute therefor a circuit adapted forconversation, whereby the operator may cut her telephone into circuitwithout restablishing the test-receiving circuit and whereby theline-circuit is subject to no undue disturbance when the test is made. iV

34. A telephone-line circuit provided with one or more spring-jackswitches or line terminals, one or each of said'switches being providedwith a testing-contact, said testing-contact being connected to one sideof the talking-circuit of said line when switched for conversation, acord-circuit terminating at one end in a plug provided withcontact-terminals adapted to register with the contacts of saidspring-jack switches, a source of current associated with saidcord-circuit and adapted to furnish current over said line when switchedfor conversation, a supervisory signal associated with said cord circuitand adapted to be operated when connection is made with a line and meansfor rendering said signal inoperative controlled by a switch at thedistant end of the line-circuit, said switch altering the flow ofcurrent over said line, a test-responsive device associated with saidcord-circuit and operated over a circuit of relatively high resistancesaid circuit being completed between the testingcontact of the test-plugand the testing-contact of said line-terminal when the line tested isswitched for conversation. an electromagnetic device associated with thesaid cord-circnit and controlling the circuit of the said supervisorysignal at one point and adapted to operate during conversation and todisconnect said test-receiving circuit and substitute therefor a circuitadapted for conversation.

35. A telephone-line circuit provided with one or more spring-jackswitches or line-terminals, ,oneor each of said switches being providedwith a testing-contact, said testingcontact being connected to one sideof the talking-circuit of said line when switched for conversation, acord-circuit terminating at one end in a plug provided withcontact-terminals adapted to register with the contacts of saidspring-jack switches, a source of current associated with saidcord-circuit and adapted to furnish current over said line when switchedfor conversation, a supervisory signal associated with said cord-circuitand adapted to be operated when connection is made with a line and meansto render said signal inoperative controlled by a switch at the distantend of the line-circuit, said switch altering the flow of current oversaid line, a test-responsive device associated with said cord-circuitand common to two or more of said cord-circuits and operated over acircuit of relatively high resistance, said circuit being completedbetween the testing-con tact of the test-plug and the testing-contact ofsaid line-tertninal when the line tested is switched for conversation,an electromagnetic device associated with the said cord-circuit andconversation, a cord-circuit terminating at one end in a plug providedwith contact-terminals adapted to register with thecontacts of saidspring-jack switches, a source of current associated with saidcord-circuit and adapted to furnish current over said line when switchedfor conversation, a test-responsive device associated with saidcord-circuit and operated over a circuit of relatively highresistance,said circnitbeing completed between the testing-contact ofthe test-plug and the testing-contact of said line-terminal when theline tested is switched for conversation, an electromagnetic deviceassociated with the cord-circuit and adapted to operate duringconversation and to disconnect said test-receiving circuit and tosubstitute therefor a circuit adapted for conversation.

37. A telephone-line circuit provided with one or more spring-jackswitches or line-terminals, one or each of said switches being providedwith a testing-contact, said testingcontact being connected to one sideof the talking-circuit of said line when switched for conversation, acord-circuit terminating at one end in a plug provided withcontact-terminals adapted to register with the contacts of saidspring-jack switches, a source of current associated with saidcord-circuit and adapted to furnish current over said line when switchedfor conversation, a test-responsive device associated with saidcord-circuit and common to two or more of said circuits and operatedover a circuit of relatively high resistance,said circuit beingcompleted between the testing-contact of the test-plug and thetesting-contact of said line-terminal when the line tested is switchedfor conversation, an electromagnetic device associated with the saidcord-circuit and adapted to operate during conversation and todisconnect said testreceiving circuit and to substitute therefor acircuit adapted for conversation.

38. A telephone-line circuit provided with one or more spring-jackswitches or line-terminals, one or each of said switches being providedwith a testing-contact, said testing-contact being connected to one sideof the talking-circuit of said line when switched for conversation, acord-circuit terminating at one end in a plug provided withcontact-terminals adapted to register with the contacts of saidspring-jack switches, a source of current associated with saidcord-circuit and adapted to furnish current over said line when switchedfor conversation, a test-responsive relay com mon to two or more of saidcord-circuits operated over a circuit including said source of currentwhen the line tested is switched for conversation, said circuit beingcompleted between said plug-testing contact and said jack-testingcontact, a relay associated with said cord-circuit and said source ofcurrent and adapted to be maintained in operation over a circuitestablished through one side of the cord-circuit when the cord-circuitis connected for conversation, said relay being adapted when operated todisconnect said test-responsive relay and to substitute therefor acircuit adapted for conversation.

39. A telephone-line circuit provided with one or more spring-jackswitches or line-terminals, one or each of said switches being providedwith atesting-contact, said testingcontact being connected to one sideof the talking-circuit of said line when switched for conversation, acord-circuit terminating at one end in a plug provided withcontact-terminals adapted to register with the contacts of saidspring-jack switches, a source of current associated with saidcord-circuit and adapted to furnish current over said line when switchedfor conversation, a supervisory signal associated with saidcord-circuitand adapted to be operated when connection is made with aline, and means to render said signal inoperative controlled by a switchat the distant end of the line-circuit, said switch altering the flow ofcurrent over said line, a test-1e sponsive relay common to two or moreof said cord-circuits operated over a circuit including said source ofcurrent when the line tested is switched for conversation, said circuitbeing completed between said plug-testing contact and said jack-testingcontact, a relay associated with said cord-circuit and said source ofcurrent and adapted to be maintained in operation over a circuitestablished through one side of the cord-circuit when the cord-circuitis connected for conversation, said relay being adapted when operated toclose at one point the circuit containing said supervisory signal and todisconnect said test-responsive relay and to substitute therefor acircuit adapted for conversation.

40. In a telephone system, the combination of a cord-circuit consistingof two talkingstrands terminating at one end in a plug adapted for thetesting and connection of telephone-lines, of a source of currentassociated therewith, a test-responsive device operated over a circuitof relatively high resistance normally connected to the testing contactof said plug, a line-terminal consisting of two contacts adapted toregister with the contacts of said plug, one of said contacts being inconnection with one side of the talking-circuit when the line isswitched for conversation, said testingcircuit including a source ofcurrent and being completed between the test-contact of the said plugand the test-contact of the said line-terminal, a relay associated withsaid cord-circuit and adapted to be maintained in operation duringconversation over-a local circuit not under the control of thesubscriber, said relay being adapted when operated to remove thehigh-resistance testing-circuit and to substitute therefor a circuitadapted for conversation.

41. In a multiple-switchboard telephoneexchange system, the combinationwith telephone-lines extending from subscribers stations to the linejacks upon the different boards or sections of a multiple switchboard,of test-thimbles for the said jacks, cord-connecting apparatus at eachboard or section of the exchange, including a connecting-plug forconnecting a calling with a called sub: scriber, a switch provided witha normal and an alternate contact, a testing-conductor terminating inthe normal contact, a test-responsive device in circuit with thetest-conductor, a test-battery connected at the remaining terminal ofthe said test-conductor while the alternate contact constitutes theterminal of the answering end of the tipstrand, a connection between theremaining terminal of the test-battery and the sleevestrands of thecord-circuits, whereby the testthimbles may be connected with the saidremaining terminal of the test-battery and circuit through the testingappliance completed upon the application of the connecting-plug to atest-thimble of a busy line, a relay in the conductor extending betweenthe test-battery and the sleeve of the connecting and testing plug, andmeans controlled by the connecting-plug and the called-subscribers jackfor closing circuit through the said relay, whereby the said switch maybe thrown from its normal test-contact to the alternate contact that isa terminal of the answeringsection of the tip-strand, whereby thecordcircuit is completed, substantially as described.

42. In a multiple-switchboard telephoneexchange system, the combinationwith telephone-lines extending from subscribers stations to theline-jacks upon the different boards or sections of a multipleswitchboard, of test-thimbles for said jacks, cord-connecting apparatusat each board or section of the exchange, including a connecting-plugfor connecting a calling with a called subscriber, a switch providedwith a normal and an alternate contact, a testing-conductor terminatingin the normal contact, a test-responsive device in circuit with thetest-conductor, a test-battery connected at the remaining terminal ofthe said test-conductor while the alternate contact constitutes theterminal of the answering end of the tip-strand, a connection betweenthe remaining terminal of the test-battery and the sleeve-strands of thecord-circuits whereby the test-thimbles may be connected with the saidremaining terminal of the test-battery and circuit through the testingappliance completed upon the application of the connecting-plug to atestthimble of a busy line, and a relay in the conductor extendingbetween the test-battery and the sleeve of the connecting and testingplug, the called subscribers telephone-line, in cooperation with hisspringjack and the connecting-plug inserted therein, serving to completecircuit through the relay to disconnect the terminal of the connectingor testing plug section ofthe tipstrand and to complete thecord-circuit, substantially as described.

43. In a multiple-switchboard telephoneexchange system, the combinationwith telephone-lines extending from subscribers stations to theline-jacks upon the different boards or sections of amultipleswitchboard, 0t test-thimbles for the said jacks, cord-connectingapparatus at each board or section of the exchange, includingaconnecting-plug for connecting a calling with a called subscriber, aswitch provided with a normal and an alternate contact, atesting-conductor terminating in the normal contact, a test-indicator incircuit with the test-conductor, a test-bat tery connected at theremaining terminal of the said testconductor while the alternate contactconstitutes the terminal of the answering end of the tip-strand, aconnection between the remaining terminal of the testbattery and thesleeve-strands of the cord-circuits, whereby the test-thimbles may beconnected with the said remaining terminal of the test-battery andcircuit through the tesb ing appliance completed upon the application ofthe connecting-plug to a test-thimble of a busy line, a relay in theconductor extending between the test-battery and the sleeve of theconnecting and testing plug, and means controlled by theconnecting-plug,and the calledsubscribers jack for closing circuitthrough the said relay, whereby the said switch may ,nate contact, atesting-conductor terminating in the normal contact, a test-indicatorincircuit with the test-conductor,a test-batteryconnected at the remainingterminal of the said test-conductor while the alternatecontactconstitutes the terminal of the answering end of the tip-strand,a connection betweenthe remaining terminal of the test-battery and thesleeve-strands of the cord-circuits whereby the test-thimbles may beconnected with the said remaining terminal of the test-battery andcircuit through the testing appliance completed upon the application ofthe connecting-plug to a test-thimble of abusy line, and a relay in theconductor extending between the test-battery and the sleeve of theconnecting and testing plug, the called subscribers telephone-line incooperation with his spring-jack and the connecting-plug insertedtherein, serving to complete circuit through the relay to disconnect theterminal of the connecting or testing plug section of the tip-strand andto complete the cord-circuit, substantially as described.

45. In a multiple-switchboard telephone exchange system, the combinationwith telephone-lines extending from subscribers stations to the linejacks upon the diiferent boards or sections of a multiple switchboard,of test-thimbles for the said jacks connected with one side of thetalking-circuit, cord-connecting apparatus at each board or section ofthe exchange comprising a plurality of cordcircuits eachhavingaconnecting-plug for connecting a calling with a calledsubscriber, a switch provided with a normal and an alternate contact, atesting-conductor having a portion common to a plurality of saidcord-circuits and terminating in the said normal contact, a test deviceresponsive to a flow of current over the test-conductor, a test-batteryhaving connection with the remaining terminal of the saidtest-conductor, the said alternate contact constituting the terminal ofthe answering end of the tip-strand of the cordcircuit, a connectionbetween the remaining terminal of the test-battery and the sleeve-'strands :of the cord-circuits, whereby when a connection is establishedthe test-thimbles are connected with the said remaining terminal of thetest-battery and circuit through the testing-conductor is completed uponthe application of the connecting-plug to a testthimble of a busy line,a relay in a conductor. extending between the test-battery and one ofthe main contacts of the connecting and testing plug, and meanscontrolled by the connecting-plug and a subscribers jack for closingcircuit through the said relay, whereby the said switch may be thrownduring an established connection from its normal test-contact to thealternate contact that is a terminal of the answering-section of thetip-strand, whereby the cord-circuit is completed, substantially asdescribed.

46. In a multiple-switchboard telephoneexchange system, the combinationwith telephone-lines extending from subscribers stations to theline-jacks upon the difierent boards or sections of a multipleswitchboard, of test-thimbles for said jacks directly connected with oneside of the talking-circuits, cord-connecting apparatus at each board orsection of the exchange, including a plurality of cord-circuits andconnecting-plugs for connecting calling and called subscribers togetherfor conversation, a switch for each cord-circuit provided with a normaland an alternate contact, a testing-conductor terminating in the normalcontact of each switch and having a portion common to a plurality ofsaid cord-circuits, a test device in the common portion of thetest-conductor and responsive to current thereover, a test-batteryhaving connection with the remaining terminal of the said test-conductorwhile the said alternate contact constitutes the terminal of theanswering end of the tip-strand of the cord-circuit,a connection betweenthe remaining terminal of the test-battery and the sleevestrands of thecord-circuits whereby the testthimbles are connected with the saidremaining terminal of the test-battery when a connection exists andcircuit through the testing device is completed upon the application ofthe connecting-plug to a test-thimble of a busy line, and a relayactuated by current from the test-battery over one of the talkingstrandsof the cord-circuit and main contact of the connecting and testing plugwhen a connection exists, said relay serving to actuate said switch todisconnect the terminal of the connecting or testing plug section of thetip-strand and to complete the cord-circuit for talking, substantiallyas described.

In witness whereof I have hereunto subscribed my name in the presence oftwo witnesses.

WILLIAM W. DEAN.

Witnesses:

MELANOTHON R. NYMAN, M. R. ROCHFORD.

